Please take a moment to review the bug reporting guidelines:
Tooltip is wrong and the CDR is working as intended. From the rework patch notes (https://heroesofthestorm.com/en-us/blog/22448179/#tyrande).
- The cooldown is lowered by 1.5 seconds every time you Basic Attack.
- The cooldown is lowered by 1.5 seconds every time you damage an enemy Hero with an ability.
“Every time Tyrande deals damage” would mean both the AA splash and ability damage to non-heroes should trigger the CDR. There’s nothing much to discuss here, really.